Advanced diabetic retinopathy and retinal detachment are two of the leading causes of blindness. Once massive vitreous hemorrhage develops from these conditions, vision is lost and surgical repair is difficult. A frequent complication is the formation of adhesions and traction bands between the vitreous and retina which produce an immobile, functionless retina. Vitreous surgery is in the early stages of development and new techniques are constantly being evaluated. The purpose of this research is to develop vitreous instrumentation which will permit the opthalmic surgeon to: (1) Introduce a CO2 laser beam (as part of the vitreous probe) directly into the vitreous cavity utilizing fiber optic techniques. This will accomplish photo-transection (cutting) of vitreoretinal adhesions as well as photocoagulation (cauterization) of neovascular vessels if bleeding occurs. (2) Utilize fiber optic techniques (as part of the vitreous probe) to simultaneously illuminate and view the vitreous cavity directly from within the eye and display the image via a video monitor. (3) Include, as part of the same vitreous probe, a system for suction and removal of vitreous hemorrhage, and reconstitution of intraocular pressure with clear vitreous substitutes. (4) Combine laser photo-transection; laser photocoagulation; fiber optic illumination and viewing; and suction and irrigation into a single miniaturized multi-function probe. (5) Test the prototype instrument, using animals eyes, to accomplish vitreous transplantation, full thickness sclera-chorioretinal wall resection for small intraocular tumors, and transvitreal chorioretinal biopsy.